1. Field of the Invention
The present invention relates to a Ni-based sintered alloy, used for forming high temperature parts in gas turbines, jet engines, etc., particularly, for forming a dynamic vane or a static vane.
2. Description of the Related Art
It is known to the art that a cast alloy or a forged alloy is generally used for forming dynamic and static vanes used under high temperature atmospheres, such as in a gas turbine or jet engine. However, these alloys are insufficient in the workability and the formability. On the other hand, a Ni-based alloy has good formability characteristics, making it possible to manufacture or repair a part-easily. Further, a Ni-based cast alloy, which exhibits the characteristics of a Ni-based alloy, is excellent in mechanical strength under high temperatures and, thus, is widely used for the manufacture of dynamic and static vanes.
It should also be noted that known parts made of a Ni-based cast alloy or a Ni-based forged alloy and used under a high temperature environment are indeed excellent in mechanical strength under high temperatures. However, if exposed to a high temperature atmospheres for a long time, the known part noted above incurs damage during the operation, due to thermal fatigue in the portion that is brought into direct contact with a high temperature gas. If the damage is found in, for example, a periodical inspection, welding or brazing is carried out for locally repairing the damaged portion.
However, if welding is carried out on the damaged portion defects such as welding cracks are generated. Also, if brazing is carried out on the damaged portion, the creep strength and thermal fatigue strength are rendered insufficient. Further, since the brazing material differs from the material of the part to be repaired, the coupling strength is weak at the interface portion between the brazing material and the portion to be repaired. Still further, since the brazing material is low in viscosity, it flows out if the repaired portion is large.